GnuPG version 2.1.12 - 2.2.11 contains a Cross ite Request Forgery (CSRF) vulnerability in dirmngr that can result in Attacker controlled CSRF, Information Disclosure, DoS. This attack appear to be exploitable via Victim must perform a WKD request, e.g. enter an email address in the composer window of Thunderbird/Enigmail. This vulnerability appears to have been fixed in after commit 4a4bb874f63741026bd26264c43bb32b1099f060.
https://usn.ubuntu.com/3853-1/
https://sektioneins.de/en/blog/18-11-23-gnupg-wkd.html
https://sektioneins.de/en/advisories/advisory-012018-gnupg-wkd.html